129 
Around the whole ovary there is a delicate 
nucleated sheath. 
Each follicular tube contains one or more egg- 
follicles in different stages of development. In the 
freshly-hatched mosquito each follicular tube contains 
an undeveloped egg-follicle. As this develops, a second 
and a third undeveloped follicle appear above it, which 
again undergo development into mature eggs. The 
follicle at first consists of two to four large cells, with 
large nuclei surrounded by a single layer of smaller 
epithelial cells (Fig. 47). 
The central cells then increase in size and number, 
so that many very large cells are contained in the now 
enlarged follicle. The surrounding epithelial cells also 
become larger, and rapidly increase in number so as to 
form a layer of regular cubical cells surrounding the 
follicle. The central cell nearest the ovarian tube 
is the ovum, the rest are nurse cells, and eventually 
disappear. Both the ovum and the nurse cells in¬ 
crease greatly in size. 
Frequently in Anophelines a large portion or the 
whole of the adult ovum consists of a mass of Sporozoa. 
These consist of numerous small cysts, each containing 
eight round or crescent-shaped bodies, each with a 
central chromatin spot (Fig. 48). 
The ovarian tube arises in the centre of the 
ovary, and receives on all sides the follicular tubes. It 
is lined with a single layer of small cubical epithelium. 
After passing out of the ovary, a considerable number 
of striated muscular fibres are arranged in a loose net¬ 
work around it, and pass from it to surrounding 
structures. 
The spermatheca consists of a chitinous sac, with 
large cells lying externally. These resemble the cells 
of the cuticle, and contain droplets. They do not 
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